Method of manufacturing a semiconductor device

ABSTRACT

A method of manufacturing a semiconductor device having a p-type field effect transistor and an n-type field effect transistor includes the steps of: forming an interface insulating layer and a high-permittivity layer on a substrate in the stated order; forming a pattern of a sacrifice layer on the high-permittivity layer; forming a metal-containing film containing metal elements therein on the high-permittivity layer in a first region where the sacrifice layer is formed and a second region where no sacrifice layer is formed; introducing the metal elements into an interface between the interface insulating layer and the high-permittivity layer in the second region by conducting a heat treatment; and removing the sacrifice layer by wet etching, wherein in the removing step, the sacrifice layer is etched easily more than the high-permittivity layer. With this configuration, the semiconductor device excellent in reliability is obtained.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2010-172900 filed onJul. 30, 2010 including the specification, drawings, and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a method of manufacturing asemiconductor device.

Japanese Unexamined Patent Application Publication No. 2009-111380discloses a technique by which different work function modulatingelements are implanted into the respective gate stacks of a PMOS regionand an NMOS region (a gate electrode and a gate insulator film).

According to this publication, a layer containing the work functionmodulating elements therein is formed over a gate electrode, and thelayer in the PMOS region is removed through the photolithography so thatonly the work function modulation elements in the NMOS region remain.Subsequently, a heat treatment is conducted on the gate stacks so thatthe work function modulating elements are implanted into the gate stack.As a result, the different work function modulating elements areimplanted into the PMOS region and the NMOS region so that the workfunctions of the respective gate stacks can be controlled.

Japanese Unexamined Patent Application Publication No. 2008-166713discloses a technique by which a dielectric layer configuring a gateinsulator film remains in only one of two regions through the lift-offtechnique.

SUMMARY

As a result of studying by the inventors, if the photolithography isused, ashing is required for peeling off a resist. However, it is foundthat when the ashing is conducted, an underlying film such as a gateelectrode is damaged by plasma, and transistor characteristicsfluctuate.

According to one aspect of the present invention, a method ofmanufacturing a semiconductor device having a p-type field effecttransistor and an n-type field effect transistor, includes the steps of:

forming an interface insulating layer and a high-permittivity layer on asubstrate in the stated order;

forming a pattern of a sacrifice layer on the high-permittivity layer;

forming a metal-containing film containing metal elements therein on thehigh-permittivity layer in a first region where the sacrifice layer isformed and a second region where no sacrifice layer is formed;

introducing the metal elements into an interface between the interfaceinsulating layer and the high-permittivity layer in the second region byconducting a heat treatment; and

removing the sacrifice layer by wet etching, and

in the removing step, the sacrifice layer is etched more easily than thehigh-permittivity layer.

According to the aspect of the present invention, the metal elementsthat modulate the work function are introduced into the interfacebetween the interface insulating layer and the high-permittivity layerin the second region with the use of the pattern of the sacrifice layer.In removing the sacrifice layer, since the removal can be conductedunder a condition in which the etching selectivity of the sacrificelayer to the high-permittivity layer of the underlying layer is high,damage on the high-permittivity layer can be reduced as compared withthe removing method using ashing. Therefore, the semiconductor deviceexcellent in reliability is obtained.

The present invention provides the manufacturing method for obtainingthe semiconductor device excellent in the reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a semiconductor deviceaccording to an embodiment of the present invention;

FIGS. 2A and 2B are cross-sectional views illustrating a manufacturingprocedure for the semiconductor device according to the embodiment ofthe present invention;

FIGS. 3A and 3B are cross-sectional views illustrating the manufacturingprocedure for the semiconductor device according to the embodiment ofthe present invention;

FIGS. 4A and 4B are cross-sectional views illustrating the manufacturingprocedure for the semiconductor device according to the embodiment ofthe present invention;

FIGS. 5A and 5B are cross-sectional views illustrating the manufacturingprocedure for the semiconductor device according to the embodiment ofthe present invention;

FIGS. 6A and 6B are cross-sectional views illustrating the manufacturingprocedure for the semiconductor device according to the embodiment ofthe present invention;

FIGS. 7A and 7B are cross-sectional views illustrating the manufacturingprocedure for the semiconductor device according to the embodiment ofthe present invention;

FIGS. 8A and 8B are cross-sectional views illustrating a manufacturingprocedure for a semiconductor device according to a comparative example;

FIG. 9 is a cross-sectional view illustrating a manufacturing procedurefor a semiconductor device according to the comparative example; and

FIGS. 10A and 10B are cross-sectional views illustrating a manufacturingprocedure for a semiconductor device according to the comparativeexample.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present invention will be describedwith reference to the accompanying drawings. In the drawings, the samecomponents are denoted by identical symbols, and their description willbe appropriately omitted.

First Embodiment

First, a first embodiment will be described.

FIG. 1 is a cross-sectional view illustrating a configuration of asemiconductor device according to this embodiment.

A semiconductor device 100 according to the first embodiment includes ap-type field effect transistor and an n-type field effect transistor,which are disposed on the same semiconductor substrate 106. In each of aPMOS region 102 and an NMOS region 104 is provided a common structure ofa gate insulating film (an interface oxide film 110, a high-permittivityfilm 112) and a gate electrode (a TiN 124, an amorphous electrode 126).In the PMOS region 102, a work function modulating metal 122 isintroduced into an interface between the interface oxide film 110 andthe high-permittivity film 112. On the other hand, in the NMOS region104, a work function modulating metal 120 different in type from thework function modulating metal 122 is introduced into an interfacebetween the interface oxide film 110 and the high-permittivity film 112.

Also, as illustrated in FIG. 1, a source drain extension region 128 anda source drain region 130 are located adjacent to a surface layer of thesemiconductor substrate 106 on both walls of each gate electrode. Also,a side wall 132 is disposed on both walls of each gate electrode.

Subsequently, a method of manufacturing the semiconductor device 100according to the first embodiment will be described. FIGS. 2A, 2B to 4A,4B are cross-sectional views illustrating a manufacturing procedure forthe semiconductor device according to this embodiment.

The method of manufacturing the semiconductor device 100 is a method ofmanufacturing a semiconductor device having a p-type field effecttransistor and an n-type field effect transistor, including thefollowing steps.

A step of forming an interface insulating layer (an interface oxide film110) and a high-permittivity layer (a high-permittivity film 112) on asubstrate in the stated order.

A step of forming a pattern of a sacrifice film 114 on thehigh-permittivity film 112.

A step of forming a metal-containing film 118 containing metal elementstherein on the high-permittivity film 112 in a first region (a PMOSregion 102) where the sacrifice film 114 is formed, and a second region(an NMOS region 104) where no sacrifice film 114 is formed.

A step of introducing the metal elements into an interface between theinterface insulating film 110 and the high-permittivity film 112 in thesecond region (the NMOS region 104) by conducting a heat treatment.

A step of removing the sacrifice film 114 by wet etching. In theremoving step in the method of manufacturing the semiconductor device100 according to this embodiment, the sacrifice film 114 is etchedeasily more than the high-permittivity film 112.

First, as illustrated in FIG. 2A, an element separation region (SiO₂film) such as an STI (shallow trench isolation) 108 is formed over amain surface of the semiconductor substrate (silicon substrate) 106through a known method.

Subsequently, the interface oxide film 110 formed by, for example,thermal oxidation, and the high-permittivity film 112 formed by, forexample, a metal organic chemical vapor deposition (MOCVD) method, arelaminated over the semiconductor substrate 106 in the stated order. Inthis embodiment, for example, SiO₂ or SiON can be used as the interfaceoxide film 110. Also, for example, HfSiON or HfO₂ can be used as thehigh-permittivity film 112.

Subsequently, the sacrifice film 114 is formed over thehigh-permittivity film 112 in the PMOS region 102 and the NMOS region104. The sacrifice film 114 is higher in the etching selectivity thanthe high-permittivity film 112. The etching selectivity is notparticularly limited, preferably 5 or more, and more preferably 10 ormore. Also, at least a part of the sacrifice film 114 includes a nitridemetal layer containing at least one element selected from a groupconsisting of titanium, aluminum, a metal element of Group III, and ametal element of Group V. In this embodiment, the sacrifice film 114 isformed of, for example, a TiN film, an AlN film, or a metal nitride filmcontaining an element of Group III or Group V therein.

Subsequently, as illustrated in FIG. 2B, a resist pattern 116 is formedover an entire surface of the sacrifice film 114, and the resist pattern116 is patterned through the photolithography. An opening portion isformed in the resist pattern 116 in the NMOS region 104. A part of thesacrifice film 114 is removed to pattern the sacrifice film 114 with apattern of the resist pattern 116 as a mask. The pattern of thesacrifice film 114 has an opening portion formed in the NMOS region 104.Then, the resist pattern 116 is peeled off with the use of a medicinalsolution containing a general organic acid therein.

Subsequently, as illustrated in FIG. 3A, a metal-containing film 118containing a metal element (hereinafter referred to as “work functionmodulating metal element”) that modulates a work function is formed overan entire surface of the high-permittivity film 112 through, forexample, an atomic layer deposition (ALD) method or a physical vapordeposition (PVD) method. The metal-containing film 118 is disposed overthe high-permittivity film 112, through the sacrifice film 114 in thePMOS region 102 (first region). On the other hand, the metal-containingfilm 118 is disposed directly on the high-permittivity film 112. Thework function modulating metal element of the metal-containing film 118is, for example, lanthanoid, yttrium, magnesium, or aluminum. In thisembodiment, La is used as the work function modulating element of themetal-containing film 118. The metal-containing film 118 is preferably ametal oxide film although being not particularly limited if themetal-containing film 118 is a film containing the work functionmodulating metal element therein. The metal-containing film 118 used inthis embodiment is La₂O₃.

Subsequently, as illustrated in FIG. 3B, in a state where themetal-containing film 118 is disposed directly on the high-permittivityfilm 112 in the NMOS region 104, a laminated structure is subjected to aheat treatment in a nitrogen atmosphere. In this situation, aconcentration of a laminated structure is preferably, for example, 100%although being not particularly limited. As a result, La that is thework function modulating metal element in the metal-containing film 118can be introduced into the interface between the interface oxide film110 and the high-permittivity film 112. In this situation, a profile ofthe work function modulating metal element increases, for example, fromthe surface layer of the high-permittivity film 112 toward theinterface.

In a process of the heat treatment, because the sacrifice film 114 ismade of a material containing nitrogen therein, the work functionmodulating metal element in the metal-containing film 118 is preventedfrom being diffused into the high-permittivity film 112 through thesacrifice film 114.

As described above, in the heat treatment process of this embodiment, asillustrated in FIG. 3B, La is diffused up to the interface surfacebetween the interface oxide film 110 and the high-permittivity film 112in a region where the sacrifice film 114 is not formed (the NMOS region104). On the other hand, in a region that is masked with the sacrificefilm 114 (the PMOS region 102), La remains in the sacrifice film 114.

Subsequently, the sacrifice film 114 is removed by wet etching with theuse of a medicinal solution such as ammonia hydrogen peroxide mixture,sulfuric acid hydrogen peroxide mixture, or hydrochloric acid hydrogenperoxide mixture. The sacrifice film 114 is high in the selectivity to,for example, HiSiON or HfO₂ as the high-permittivity film 112. For thatreason, damage on the high-permittivity film 112 can be suppressed whenthe sacrifice film 114 is subjected to wet etching.

Sequentially, the excessive La (the metal-containing film 118) and thesacrifice film 114 are moved. As a result, a structure is obtained inwhich La (a work function modulating metal 120) exists in the interfacebetween the interface oxide film 110 and the high-permittivity film 112in only the NMOS region 104 (FIG. 4A).

Continuously, the same processes as those in FIGS. 2A to 4A areconducted on the PMOS region 102 side. In this situation, Al differentfrom La on the NMOS region 104 side is used as the work functionmodulating metal element. As a result, as illustrated in FIG. 4B, astructure is obtained in which the work function modulating metal 122(Al) is introduced into the interface between the interface oxide film110 and the high-permittivity film 112 in the PMOS region 102. Also, inthe structure, the work function modulating metal 120 different in typefrom the work function modulating metal 122 is introduced into theinterface in the NMOS region 104.

Continuously, a normal semiconductor manufacturing process is conductedto form the structure illustrated in FIG. 1. That is, a TiN (titaniumnitride) film is formed over the entire surface through a reactivesputtering method of a Ti target of the Ti target. The TiN 124 may beformed through the CVD method or the ALD method instead of thesputtering method. An amorphous Si film is formed over the TiN film.Subsequently, the amorphous Si film and the TiN film are subjected toRIE (reactive ion etching) processing with the use of a hard mask (notshown) to form the TiN 124 and the amorphous electrode 126.Subsequently, B ions are implanted into a p-channel region with the useof a resist not shown, and similarly P or As ions are implanted into ann-channel region with the use of a resist mask. Then, a heat treatmentis conducted to form the source drain extension region 128. With the useof the CVD method and the RIE method, the side wall 132 having twolayers of a SiO₂ film and a silicon nitride film is formed. Thereafter,B ions are implanted into the p-channel region with the use of a resistnot shown, and similarly P or As ions are implanted into an n-channelregion with the use of a resist mask not shown. Then, a heat treatmentis conducted to form the source drain extension region 130.Continuously, a silicide film is formed over surfaces of the sourcedrain region 130 and the amorphous electrode 126 through a knownsalicide process in a self-aligning manner. As a result, a gateelectrode having a laminate structure of FIG. 1 is formed. Thereafter,the semiconductor device 100 according to this embodiment is obtained byconducting formation of an interlayer insulating film, opening andembedding of a contact hole, and formation of wirings as applied to therelated-art transistor. In this embodiment, a laminate structure of theTiN 124 and the amorphous electrode 126 is used as the gate electrode.However, the present invention is not limited to this configuration, butvarious metal gates can be used.

Subsequently, the action and effects of the first embodiment will bedescribed. In the first embodiment, in removing the sacrifice film 114,since the removal can be conducted under a condition in which theetching selectivity of the sacrifice layer 114 to the high-permittivitylayer 112 of the underlying layer is high, damage on thehigh-permittivity layer 112 can be reduced as compared with the methodof removing the resist by ashing. Therefore, the semiconductor device100 that is reduced in the fluctuation of the transistor characteristicand excellent in reliability is obtained.

Also, in the first embodiment, the different work function modulatingmetals can be introduced into the interface between the interface oxidefilm 110 and the high-permittivity film 112 in the respective PMOSregion 102 and NMOS region 104. As a result, the threshold values of thep-type field effect transistor and the n-type field effect transistorover the same semiconductor substrate can be controlled to respectivedesired values.

Subsequently, the advantages of the present invention will be furtherdescribed with reference to comparative examples illustrated in FIGS. 8to 10.

In a process of the comparative example, as in Japanese UnexaminedPatent Application Publication No. 2009-111380, a metal-containing film18 containing the work function modulating metal therein is formed overthe NMOS region other than a PMOS region 2 with the use of a resistpattern 16. That is, the comparative example is different from thisembodiment in that not the sacrifice film 114 but the resist pattern 16is used.

Subsequently, a flow of the process in the comparative example will bedescribed. As illustrated in FIG. 8A, an interface oxide film 10 and ahigh-permittivity film 12 are laminated in the stated order on asemiconductor substrate 6 in which a PMOS region 2 and an NMOS region 4are provided through an STI 8. Subsequently, the metal-containing film18 (La₂O₃) is formed directly on the overall surface of thehigh-permittivity film 12. Then, as illustrated in FIG. 8B, a pattern ofthe resist pattern 16 is formed over the metal-containing film 18through the photolithography. Then, as illustrated in FIG. 9, themetal-containing film 18 in the PMOS region 2 is removed with the resistpattern 16 as a mask, and only the metal-containing film 18 remain inthe NMOS region 4. Thereafter, the resist pattern 16 over themetal-containing film 18 is removed by ashing in a state where thehigh-permittivity film 12 in the PMOS region 2 is exposed.

In the above comparative example, it is found by studying by theinventors that the following two transistor characteristics mainlyfluctuate. First, because the high-permittivity film 12 of theunderlying layer is exposed, when the resist pattern 16 is removed byashing, the high-permittivity film 12 may be nitrided or increased, orplasma damage may occur in the high-permittivity film 12. Also, second,when the resist is coated over the metal-containing film 18, carbon ornitrogen in the resist may react with La that is the work functionmodulating metal to generate a reactant such as La—F. The reactantinterferes with peeling off of La or diffusion of La. In this way, inthe comparative example in which a pattern of the layer containing Latherein is formed through the photolithography, various transistorcharacteristics (electric characteristics) may fluctuate.

Also, in the comparative example, there is a case in which such a reworkthat the above process is again reworked when misalignment occurs. Inthis case, as illustrated in FIG. 10A, the metal-containing film 18 isfirst removed once. However, in this situation, a reactant 22 of theresist and La, and a residue 20 of La remain on the high-permittivityfilm 12. On this high-permittivity film 12 is formed themetal-containing film 18 (FIG. 10B), and the processes illustrated inFIGS. 8B and 9 are repeated. For that reason, the fluctuation of theabove-mentioned two transistor characteristics may further increase.

On the contrary, in this embodiment, in order to form a pattern of themetal-containing film 118 containing La therein, the sacrifice film 114is used without using the photolithography. For that reason, in thisembodiment, the reactant of La due to the resist is not generated. Also,since the sacrifice film 114 is disposed over the high-permittivity film112, the La residue is not generated over the high-permittivity film112. Also, since there is no process of peeling off the resist by ashingin the state where the surface of the high-permittivity film 112 isexposed, the high-permittivity film 112 is not nitrided and increased,and no plasma damage occurs in the high-permittivity film 112. That is,in this embodiment, the variation of the transistor characteristics,which occurs in the process of the comparative example, can besuppressed. Also, since the high-permittivity film 112 is not exposed,the fluctuation of the transistor characteristic due to the rework isalso suppressed.

Second Embodiment

Subsequently, a second embodiment will be described.

FIGS. 5A, 5A to 7A, 7B are cross-sectional views illustrating amanufacturing procedure of a semiconductor device according to a secondembodiment.

A method of manufacturing the semiconductor device 100 according to thesecond embodiment is identical with that in the first embodiment exceptfor a step of forming a sacrifice film 134. That is, a step of forming apattern of the sacrifice film 134 in the method of manufacturing thesemiconductor device 100 includes a step of forming a metal layer (thesacrifice film 134) containing at least one element selected from agroup consisting of Ti, Al, a metal element of Group III, and a metalelement of Group V therein, a step of forming a pattern of the sacrificefilm 134, and a step of nitriding a surface layer of the sacrifice film134.

First, as illustrated in FIG. 5A, as in the first embodiment, theinterface oxide film 110 and the high-permittivity film 112 arelaminated over the semiconductor substrate 106 in the PMOS region 102and the NMOS region 104. Subsequently, the sacrifice film 134 is formedover the high-permittivity film 112. The sacrifice film 134 is not yetnitrided, and for example, at least one element selected from the groupconsisting of Ti, Al, the metal element of Group III, and the metalelement of Group V can be provided as the metal layer. Subsequently, thesacrifice film 134 is patterned with the use of the resist pattern 116.In this situation, since the sacrifice film 134 is not nitrided, thepatterning is facilitated.

Subsequently, as illustrated in FIG. 5B, the surface layer of thepatterned sacrifice film 134 is subjected to a nitriding process. As aresult, a nitride layer 136 is formed over the surface layer of thesacrifice film 134.

The subsequent processes are identical with those in the firstembodiment. That is, the metal-containing film 118 containing the workfunction modulating metal element is formed over the nitride layer 136in the PMOS region 102 and over the high-permittivity film 112 in theNMOS region 104 (FIG. 6A). Subsequently, a heat treatment is conducted,and the work function modulating metal 120 (La) is introduced into theinterface between the interface oxide film 110 and the high-permittivityfilm 112 in the NMOS region 104 (FIG. 6B). Subsequently, themetal-containing film 118, the sacrifice film 134, and the nitride layer136 are removed as in the first embodiment (FIG. 7A). Thereafter, theprocesses of FIGS. 5A to 7A are conducted in the PMOS region 102, and asillustrated in FIG. 7B, a structure is obtained in which the workfunction modulating metal 122 (Al) is introduced into the interfacebetween the interface oxide film 110 and the high-permittivity film 112in the PMOS region 102. Then, the normal process of manufacturing thesemiconductor device is conducted to obtain the semiconductor device 100illustrated in FIG. 1.

In the second embodiment, the metal film that is not nitrided is usedfor the sacrifice film 134. As a result, the sacrifice film 134 iseasily patterned to enhance the process stability. Also, the patternedsacrifice film 134 is subjected to a nitriding process whereby thenitride layer 136 can be formed over the surface layer of the sacrificefilm 134. The sacrifice film 134 can prevents La from diffusing in thehigh-permittivity film 112 in the PMOS region 102. Similarly, in thesecond embodiment, the same advantages as those in the first embodimentare obtained.

Third Embodiment

A third embodiment is identical with the first embodiment except thatthe step of removing the sacrifice film 114 through the lift-off methodis different.

In the third embodiment, in the step illustrated in FIG. 3A, thesacrifice film 114 is removed whereby only the metal-containing film 118in the PMOS region 102 can be removed. Through the above lift-offmethod, the metal-containing film 118 can be made to remain over onlythe high-permittivity film 112 in the NMOS region 104. Thereafter, thework function modulating metal 120 can be introduced into the interfacebetween the interface oxide film 110 and the high-permittivity film 112in only the PMOS region 102 by a heat treatment.

With the above processes, the third embodiment can obtain the sameadvantages as those in the first embodiment.

The above-mentioned embodiments and plural modified examples can becombined together unless the contents thereof conflict each other. Also,in the above-mentioned embodiments and modified examples, the structuresof the respective parts have been described in detail. Those structurescan be variously changed without departing from the subject matter ofthe present invention.

What is claimed is:
 1. A method of manufacturing a semiconductor devicehaving a p-type field effect transistor and an n-type field effecttransistor, said method comprising: forming an interface insulatinglayer and a high-permittivity layer on a substrate in the stated order;forming a pattern of a sacrifice layer on the high-permittivity layer;forming a metal-containing film containing metal elements therein on thehigh-permittivity layer in a first region where the sacrifice layer isformed and a second region where no sacrifice layer is formed;introducing the metal elements into an interface between the interfaceinsulating layer and the high-permittivity layer in the second region byconducting a heat treatment; and removing the sacrifice layer by wetetching, wherein in the removing the sacrifice layer is etched easilymore than the high-permittivity layer; wherein the step of forming thepattern of the sacrifice film includes: forming a metal layer containingat least one element selected from a group consisting of Ti, Al, a metalelement of Group III, and a metal element of Group V therein; forming apattern of the metal film; and nitriding a surface layer of the metalfilm.